Conventional scroll compressors include a fixed scroll with a spiral-shaped wall portion provided on a first side of an end plate and an orbiting scroll with a wall portion on a first side of an end plate with essentially the same spiral shape as that of the wall portion of the fixed scroll. The first sides of the end plates of the fixed scroll and the orbiting scroll are brought to face one another to assembly the wall portions together. In this mated state, the orbiting scroll orbits about the fixed scroll to gradually reduce the volume of the compression chamber formed between the wall portions and compress the fluid in the compression chamber.
An example of a conventional scroll for a compressor is described in the method of manufacturing a scroll compressor of Patent Document 1. In Patent Document 1, a fixed scroll and/or an orbiting scroll is rendered with a plurality of minute recesses on the side (wrap side) opposite the end plate (end cover) by being jetted with a fluid containing abrasive particles. This is to help with the retention of lubricating oil on the surface.
Additionally, for example, in the method of enhancing residual stress of a metallic material described in Patent Document 2, to prevent stress corrosion cracking at a weld portion of the metallic material and nearby, a fluid flow containing cavitation bubbles is impinged on the surface of the metallic material, the cavitation bubbles being generated by cavitation via water jet. The impact force generated by the collapse of the cavitation bubbles imparts compressive residual stress to the metallic material.